Generally, as the scale of industry expands and the standard of living elevates, the amount of household waste including industrial waste increases, and therefore, the development of waste disposal plans or systems are actively progressed.
Particularly, most of the food waste, which has been socially seriously raised among the household waste, includes moisture and bad smell and easily decays with the passage of time.
One of the methods for disposing of the food waste is to bury it in a landfill. However, when the food waste is buried, the moisture included in the food waste contaminates soil and leaches into and contaminates a stream, river or water supply source.
To solve the aforementioned problems, Korean Patent Publication No. 10-0283682 (hereinafter, referred to as “Prior Art 1”) discloses a “hot-air drying apparatus”.
In Prior Art 1, the hot-air drying apparatus comprises a dryer 11 including a first tumbling barrel, second tumbling barrel and third tumbling barrel. Rollers 14, 14′, which are supported to be rotatable by guide rollers 12, 12′ positioned at one end of the first tumbling barrel and are driven by a chain belt (A) connected with a motor 13, are installed to rotate in contact with the outer surface of the other end of the first tumbling barrel. Agitation wings 19b, 19c, 20b, 20c are positioned at the inner and outer surfaces of the second and third tumbling barrels. The waste which is put into a hopper 3, 25 is dried by the hot air of a burner 2, 24 and the dried waste moves out through an outlet 17. In the hot-air drying apparatus, the dryer 11 is connected to a heater 1 at one end and to a cyclone centrifugal dust collector 22 at the other end by fitting a portion of an inlet 21 of the cyclone centrifugal dust collector 22 into the outlet 17 of the dryer 11.
In Prior Art 1, it is possible to reduce the consumption amount of energy to be combusted by the heater which is double-layer or triple-layer formed to make the food waste and agricultural sludge as resources upon drying. Simultaneously, the heater is efficiently cooled by air which flows into through an outside heating furnace. In the dryer including the three tumbling barrels, as the food waste swirls and proceeds, the moisture included in the food waste evaporates and the stinky smell of the food waste is removed in the third tumbling barrel, and the moisture content of the dried waste is uniform in the first and second tumbling barrels. As the dried waste finally passes through the cyclone centrifugal dust collector, the moisture content of the dried waste is controlled to be 60%˜10%. Also, the food waste and agricultural sludge are processed by 2 ton˜10 tons per hour.
However, Prior Art 1 has the problem in that, since the source of heat energy required for the drying process is raw chemical materials, a maintenance cost is excessively high.